This proposal is submitted to request support for continuing research into the development of an antithrombogenic membrane oxygenator which would allow long-term perfusion without the need for systemic heparinization. In previous research in our laboratory we have demonstrated that heparin can be chemically bound to membrane oxygenators and tubing systems. We have perfused animals for periods up to 48 hours without deleterious effects or clot formation. We are proposing to continue this research to achieve longer periods of perfusion and if proven to be safe, apply this to patients who are suffering from severe respiratory insufficiency. If proven successful, this will allow the machinery to be used for long-term cardiorespiratory support in patients with severe respiratory insufficiency from acute causes and in infants with hyaline membrane disease. It likewise could be used for open heart operations and avoid systemic heparinization of the patient.